Fusing IGBT-Based Inverters

The number of applications based on the dc-link voltage source converter is in a continuous growth. Due to the fact that the power level increases more energy is stored in the dc- link. Even with an active protection, a high power IGBT still has a risk of exhibiting a violent rupture in the case of a fault. In order to avoid the rupture a possible solution is to use a fuse protection of the converter. From failure analysis of a three-phase inverter, a dc-link location for fuses might assure a protection against all faults. Experiments made with 400 A, 1200 V IGBT switches show that rupture can be avoided by the use of high-speed fuse protection. The problem of added inductance in existing High- Speed Fuses is discussed, and new IGBT Typower fuses in the dc-link circuit are treated. Finally, some considerations about current distribution in dc-link fuses and spectral analysis of these currents are discussed when high- frequency components are present in the current.